As a plate member shearing apparatus for shearing a long belt-shaped plate member into a predetermined length, the so-called flying shear is widely used.
As a conventional flying shear, there are two types, a single shearing type and a double shearing type. In a single shearing type flying shear, a single shearing blade shears a long plate member into a predetermined length while moving the plate member in the longitudinal direction thereof. On the other hand, in the double shearing type flying shear, a pair of shearing blades disposed at a certain distance in the traveling direction of a long plate member shear the plate member into a predetermined length while moving the plate member.
However, according to the single shearing type flying shear, since the traveling speed of the plate member fluctuates slightly, the shearing length of the plate member changes due to the fluctuations of the traveling speed. Therefore, it was difficult to shear the plate member into a predetermined length.
On the other hand, according to the double shearing type flying shear, since the plate member is sheared in a state that the tip portion thereof remains, the remaining piece (the so-called scrap) is generated at the tip portion of the plate member whenever the plate member is sheared. Accordingly, the yielding efficiency of the sheared piece is low.
Furthermore, in such a flying shear, since a forwarding operation of the plate member is performed only by an electric controller, there is a limitation in improving the shearing speed.
The present invention was made in view of the aforementioned technical background, and aims to provide a plate member shearing apparatus high in yielding efficiency of a sheared piece and capable of shearing a plate member into a uniform length, a method for shearing a plate member and a sheared piece of a plate member.
Other objects and advantages of the present invention will be apparent from the following preferred embodiments.